1. Field of the Invention
Generally speaking, the invention relates to apparatus and processes for long term, ambulatory monitoring and accumulation of human physiological data. More specifically, the invention disclosed herein consists of a miniature, solid state recorder for ambulatory monitoring of body signals over extended periods of time, sealed against moisture and mounted under all clothing, and supported on a bridge between at least two adhesively attached sensor electrodes in conductive contact with the skin. Provision for direct mounting of the solid state recorder is made possible by the recorder's light weight and flexible structure, and by recent advances in the manufacture of very small memory chips and subminiature solid state, lightweight processor chips incorporated in the invention. The invention not only provides for recording and storing physiological data, but also provides the sensor data input mounts as well as a data output terminal to transfer stored information to a data processing and display unit.
2. Description of the Prior Art
Many and varied long term ambulatory monitoring devices and systems have been developed and marketed over the years with numerous improvements made by applicant herein; most dealing with improved means to provide to the physician a higher and higher accuracy in the assessment of a patient's risk of sudden death from arrhythmia and other life threatening signal abnormalities. The monitoring process, as applied to electrocardiography, was named after its inventor and pioneer research physicist, Norman J. Holter, President of the Holter Research Foundation of Helena, Montana. Holter's coinventor and technical assistant on the original Holter concept was Wilford R. Glasscock. The original Holter concept and invention was assigned to Del Mar Engineering Laboratories of Los Angeles, Calif., under technology license from the Holter Research Foundation dated Apr. 19, 1962, and was filed in the US Patent and Trademark Office by assignee, Del Mar, on Jul. 6, 1962. The application issued as U.S. Pat. No. 3,215,136 on Nov. 2, 1965 and taught not only a long term, ambulatory ECG recording technique but also Holter's data reduction and presentation format promoted under Del Mar's US registered trademarks Electrocardiocorder.RTM., AVSEP.RTM., and Arrhythmiagraph.RTM.. The 136 patent specifically taught a means for processing electrocardiographic signals and more particularly to a means for obtaining large quantities of electrocardiac signals and to a means for facilitating the processing and observing in graphic form of large volumes of such signals in a short interval of time.
Based on the presentations set forth in the foregoing 136 Holter patent, Del Mar Engineering Laboratories produced for clinical cardiology the first complete Holter Monitoring Systems in 1963 which immediately inspired research activity of pioneer research cardiologists: Dr. Eliot Corday, Dr. Lawrence E. Hinkle, Dr. Herman K. Hellerstein and Dr. John S. Gilson. As a result of several years of clinical testing by these physicians of the Holter Monitoring procedure resulting in numerous publications in medical journals on results emanating from test on hundreds of patients, Holter Monitoring was endorsed and recommended as a new revelation in cardiovascular clinical practice, and was eventually adopted as a standard practice worldwide.
Since 1965, a progression of Holter improvement patents have issued over the years, notably that of Oct. 31, 1978, U.S. Pat. No. 4,123,785, "Recorder for Cardiac Signals with Manually Activated Event Marker" by inventors Issac R. Cherry and Donald L. Anderson of Del Mar Avionics, successor to Del Mar Engineering Labs. The 785 patent disclosed a small, hip/side mounted tape recorder for ambulatory recording of cardiac signals over a twenty-four hour interval and included a clock with visual display and a patient event marker. Cardiac signals are simultaneously recorded on two tracks on magnetic tape wherein the event marker function could also be recorded and activated by the patient to denote the happening of a specific event sensed by the patient that can be easily recognized on play back in relation to heart activity at the time. The 785 Cherry et al. patent was followed by yet many other noteworthy inventions.
The forgoing US patents taught many important developments in Holter Monitoring technology but were yet followed by a series of other prior patents of Del Mar Avionics dealing with Holter Monitoring concepts. U.S. Pat. No. 4,532,934, was issued August 1985, titled "Pacemaker Monitoring Recorder and Malfunction Analyzer", by inventor George J. Kelen, M.D. The Kelen 934 patent disclosed a hip/side mounted magnetic tape recorder which detects and records sequential pacemaker spikes in one channel in a waveform compatible with corresponding ECG signals recorded in a second tape channel. The system further includes an analysis module connected to the playback unit for receiving both the ECG and pacer spike signals and is adapted to play back both channels of information at 120 times recording speed. An analysis module in the recorder has counters to accumulate the number of paced beats and fusion beats. The system is further configured to sense malfunctions, failure to sense, failure to capture, and abnormal bradycardia.
U.S. Pat. No. 5,109,862 issued May 8, 1992 and was titled "Method and Apparatus for Spectral Analysis of Electrocardiographic Signals," by inventors George J. Kelen, M.D. and Raphael Henkin, Ph.D. The Kelen 862 patent discloses a signal processing and analysis method and apparatus for plotting and measuring ECG signals where the graphic plots and numeric parameters measured reveal abnormalities of electrical conduction within the heart thought to anticipate abnormal heart rhythm, arrhythmia. The invention employs Fourier analysis of short overlapping segments of ECG signal to create a three dimensional electrocardiogram map.
U.S. Pat. No. 5,205,295, issued Apr. 27, 1993 "Method and Apparatus for Holter Recorder with High Resolution Signal Averaging Capability for Late Potential Analysis," by inventors Bruce Del Mar and Isaac R. Cherry. The Del Mar 295 patent discloses a method for digital signal averaging of selected signals and storing for future playback. The averaged signals, several times per hour in a 24 hour period, are correlated with previously defined correlation coefficients to yield summated results that have eliminated nonrepetitive noise. Information so accumulated enable micropotential analysis of cardiac electrical activity.
Since 1996 digital data storage capacity in lightweight disc drives and printed circuit card, flash memory components has progressed in production to the point where solid-state ambulatory physiological recorders can be made at reasonable cost. They offer an advantage over ambulatory physiological tape recorders having no moving parts and no need for separate analog-to-digital data conversion. Solid-state recording now represents a formidable improvement in the art of ambulatory physiological recording.
Long-term ambulatory physiological and Holter recorders have been conventionally worn in a protective pouch slung by straps over the shoulder outside the clothing or hung on a person's belt, again outside the clothing. Many problems and inconveniences can occur while wearing such conventional ambulatory physiological recorders, especially because of the necessary prolonged, continuous recording times involved. Dressing and sleeping become troublesome because of the long wire harness required on existing recorders. Electrodes often get pulled off the chest by the wire harness during sleep and active physical activities. The recorder may also receive rough treatment from dropping to the floor or exposure to other hostile environments. With the invention disclosed herein, compactness and simplicity replace a variety of components and complication. With the new invention disclosed herein, exercise, including walking and running, is unrestricted. The daily routine of sleeping, dressing and bathing need not change! And, for the clinician, this invention can create more reliable long-term monitoring of physiological signal.